In a multiple air conditioner, which is a conventional air-conditioning apparatus, cooling energy or heating energy is delivered indoors by circulating a refrigerant between an outdoor unit, which is a heat source apparatus installed outdoors, and an indoor unit installed indoors. As for the refrigerant, an HFC (hydrofluorocarbon) refrigerant is mainly used and the air-conditioning apparatus using a natural refrigerant such as CO2 is proposed.
In a chiller, which is another conventional air-conditioning apparatus, cooling energy or heating energy is generated in a heat source apparatus disposed outdoors, cooling energy or heating energy is transferred to a heat medium such as water and an anti-freezing liquid at a heat exchanger disposed in an outdoor unit, and cooling operation or heating operation is performed by carrying the heat medium to a fan coil unit, a panel heater and the like, which are of an indoor unit (Refer to Patent Literature 1, for example).
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2003-343936